The premiere of BBC One's buzzy new thriller The Replacement left viewers on the edge of their seats!

Expectations were high even before the three-part drama aired, since it's the latest from Ultraviolet, Da Vinci's Demons and Doctor Who writer Joe Ahearne.

In a twist on Single White Female for the social media generation, new mum Ellen (Lost in Austen's Morven Christie) slowly starts to fear that her maternity cover Paula (Broadchurch's Vicky McClure) has sinister plans to take over her life. And then a friend turns up dead!

Earlier this week, writer Joe Ahearne wrote in a BBC blog post that he'd wanted to capitalise on the fears we face in everyday life to craft his thriller - rather than simply rely on mystery genre conventions.

"Someone going on maternity leave and having to deal with a temporary replacement seemed like a great way to explore this emotion," he explained. "She watches what's going on around her and sees evidence everywhere she looks that she's being undermined.

"Everyone can identify with the anxiety of seeing someone do their job as good or better than you can. The pang when a colleague invites another colleague for lunch and doesn't tell you. Most of us have the secret fear that we're not good enough and feel envy when we see others navigating professional and social situations more suavely than we think we can manage.

"The Replacement turns that up to 11. The fact it's a pregnant woman going through this intensifies the dilemma. Women get attacked from every side when they make decisions about how to manage the change in their life. Whatever decision they make is challenged and dissected. It's the perfect landscape for paranoia and suspense."

The Replacement continues next Tuesday at 9pm on BBC One as Ellen investigates Paula's shady past as she returns to work.